CN113353956A - System and method for co-processing fly ash by washing and desalting and combining with cement kiln - Google Patents
System and method for co-processing fly ash by washing and desalting and combining with cement kiln Download PDFInfo
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Abstract
The invention relates to a system and a method for cooperative treatment of a fly ash washing desalination combined cement kiln, wherein the system mainly comprises: the device comprises a fly ash elution unit, an eluent purification unit, a drying unit, an evaporation salt-making unit and a kiln-entering calcination unit, wherein an eluent outlet of the fly ash elution unit is connected with an inlet of the eluent purification unit, an outlet of the eluent purification unit is connected with an inlet of the evaporation salt-making unit, an elution ash outlet of the fly ash elution unit is connected with the drying unit, and an outlet of the drying unit is connected with the kiln-entering calcination unit; the method adopts a special multistage countercurrent rinsing technology to remove chlorine salt in the fly ash to prepare industrial salt; the elution ash is calcined in a cement kiln, heavy metals are completely solidified in clinker lattices, dioxin is thoroughly decomposed, and secondary synthesis conditions are not available; high-temperature flue gas is subjected to multi-stage adsorption and dust collection and then reaches the standard and is discharged; the eluent is recycled after being treated, and zero emission is realized; the reduction, the resource utilization and the harmlessness of the fly ash treatment are completely realized.
Description
Technical Field
The invention belongs to the field of harmless treatment and resource utilization of hazardous wastes, and particularly relates to a system and a method for cooperative treatment of fly ash by washing and desalting in a combined cement kiln.
Background
At present, the garbage disposal mode mainly comprises landfill and incineration. In terms of landfill, the garbage landfill not only occupies a large amount of land resources, but also can generate pollution harm to soil and underground water at any time like a bomb; although the reduction and resource treatment of the garbage are realized by the garbage incineration, a large amount of fly ash which is toxic, harmful and difficult to dispose is still generated.
At present, fly ash is mainly treated by cement solidification or chemical stabilization, landfill and high-temperature stabilization. In terms of landfill, a large amount of land resources are required to be occupied, the long-term effect of the landfill has a large risk, and underground water and soil are easily polluted; with the increasing shortage of urban construction land and the increasing demand of ecological environment, the landfill treatment of waste incineration fly ash has been prohibited by various governments. The high-temperature stabilization treatment includes high-temperature melting, high-temperature sintering and cement kiln cooperative treatment, the high-temperature stabilization treatment technology can remove harmful substances such as heavy metal, dioxin and the like in the fly ash at high temperature, and the slag can be used as materials of civil engineering, cement, buildings and the like. Therefore, the high-temperature stabilization treatment of fly ash has been a hot spot for research, application, and management, and has been widely used in developed countries such as the united states and germany.
Compared with European and American countries, the content of soluble chlorine salt in the waste incineration fly ash in China is high, secondary pollution caused by escape of hydrogen chloride gas is difficult to control by fusion sintering, the fly ash with the chloride ion content below 3% is only suitable for cooperative treatment by direct injection into a cement kiln, kiln skinning and equipment and pipelines corrosion can be caused by poor control of the speed of the fly ash entering the kiln, and meanwhile, a high-chlorine material discharged by a bypass air discharge bypass is a treatment difficulty. In view of the characteristic of high content of soluble chloride in fly ash in China, the fly ash needs to be pretreated for removing the soluble chloride before high-temperature stabilization treatment, so that the soluble chloride in the fly ash is removed.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a system and a method for the cooperative treatment of a fly ash washing and desalting combined cement kiln, wherein the fly ash washing and desalting technology is coupled with the fly ash cooperative treatment technology of the cement kiln, so that the problems that the content of soluble chloride salt in the fly ash from waste incineration in China is high, the fly ash with the chloride ion content below 3 percent is only suitable for the cooperative treatment of the fly ash by directly injecting into the cement kiln, the kiln is skinned and corrodes equipment and pipelines due to poor control of the speed of the fly ash entering the kiln, and meanwhile, a high-chlorine-content material discharged by a bypass air discharging bypass is a treatment difficulty are solved.
In order to solve at least one of the above problems, the invention adopts the technical scheme that:
the system for the cooperative disposal of the fly ash washing desalination combined cement kiln is characterized in that an eluent outlet of a fly ash eluting unit is connected with an inlet of an eluent purification unit, an outlet of the eluent purification unit is connected with an inlet of an evaporation salt-making unit, an eluting ash outlet of the fly ash eluting unit is connected with a drying unit, and an outlet of the drying unit is connected with a calcining unit entering the kiln.
The fly ash elution unit comprises a mixer, a water washing reactor and an elution ash/liquid separator, wherein a fly ash inlet of the mixer is respectively connected with an outlet of the fly ash metering device and an outlet of the water distribution metering device, an outlet of the mixer is connected with the water washing reactor, an outlet of the water washing reactor is connected with an inlet of the elution ash/liquid separator, an elution ash outlet of the elution ash/liquid separator is connected with the drying unit, and an eluent outlet of the elution ash/liquid separator is connected with the eluent purification unit.
The eluent purification unit comprises a heavy metal removal reactor, a hardness removal reactor, a concentration and precipitation device, a precipitate removal device, a multistage filtering device and a Ph adjusting device, wherein an inlet of the heavy metal removal reactor is connected with an eluent outlet of the elution ash/liquid separator, an outlet of the heavy metal removal reactor is connected with the hardness removal reactor, an outlet of the hardness removal reactor is connected with an inlet of the precipitate removal device, a precipitate outlet of the precipitate removal device is connected with the water washing reactor, an eluent outlet of the precipitate removal device is connected with an inlet of the concentration and precipitation device, an underflow outlet of the concentration and precipitation device is connected with the hardness removal reactor, an overflow outlet of the concentration and precipitation device is connected with an inlet of the multistage filtering device, an outlet of the multistage filtering device is connected with an inlet of the Ph adjusting device, and the outlet of the Ph adjusting device is connected with the inlet of the evaporation water supply tank.
The evaporation salt-making unit comprises a preheating heat exchanger, a steam compressor, a crystallization separator, a thickener, an enamel kettle, a sylvite centrifuge, a sylvite mother liquor tank, a sylvite mother liquor heat exchanger, a sodium mother liquor tank, a sodium salt centrifuge, a forced circulation evaporator, a gas-liquid separator, a falling-film evaporator and a distilled water tank, wherein the outlet of an evaporation water supply tank is connected with the preheating heat exchanger, the outlet of the preheating heat exchanger is connected with the falling-film evaporator, the outlet of the falling-film evaporator is respectively connected with the gas-liquid separator and the forced circulation evaporator, the outlet of the gas-liquid separator is connected with the steam compressor, the outlet of the steam compressor is respectively connected with the falling-film evaporator and the forced circulation evaporator, the outlet of the forced circulation evaporator is connected with the outlet of the crystallization separator, and the outlet of the crystallization separator is respectively connected with the steam compressor, the potassium salt tank, the evaporator and the evaporator are respectively, The thickener is connected with the sodium salt centrifugal machine and the enamel kettle respectively, an outlet of the sodium salt centrifugal machine is connected with the sodium mother liquor tank, an outlet of the enamel kettle is connected with the potassium salt centrifugal machine, the potassium salt centrifugal machine is connected with the potassium mother liquor tank, the potassium salt mother liquor tank is connected with the potassium mother liquor heat exchanger, and the forced circulation heat exchanger is connected with the sodium mother liquor tank and the potassium mother liquor heat exchanger respectively.
The drying unit comprises a washing fly ash conveyor, a washing fly ash feeder, a washing fly ash dryer and a drying fly ash collector, wherein the outlet of the washing fly ash conveyor is connected with the inlet of the washing fly ash feeder, the outlet of the washing fly ash feeder is connected with the inlet of the washing fly ash dryer, the outlet of the washing fly ash dryer is connected with the inlet of the drying fly ash collector, and the outlet of the drying fly ash collector is connected with the calcining unit in the kiln.
The kiln entering calcining unit comprises a dry fly ash hoist, a kiln entering fly ash metering device and a cement kiln, wherein the outlet of the dry fly ash hoist is connected with the kiln entering fly ash metering device, and the outlet of the kiln entering fly ash metering device is connected with the cement kiln.
Therefore, the system for the co-processing of the fly ash washing desalination and cement kiln disclosed by the embodiment of the invention has the advantages that the washing dechlorination technology is coupled with the high-temperature calcination technology of the cement kiln, and a special multistage countercurrent rinsing technology is adopted, so that the dechlorination effect is good, the water consumption is low, and no dust is raised. The method adopts alkaline elution and secondary heavy metal trapping, so that the transfer of heavy metals and dioxin in the fly ash is low; the MVR evaporation desalination technology is adopted, salt is produced as a byproduct, and condensed water is recycled, so that the energy consumption is low and no pollution is caused; the fly ash is dried by adopting the waste heat of the cement kiln, so that the interference of the fly ash to the cement kiln is reduced, the energy is saved, and the emission is reduced; the fly ash is calcined at high temperature by adopting the cement kiln, so that the heavy metal and dioxin are thoroughly treated, and the method is safe and environment-friendly and has no aftereffect. The technology extracts chloride in fly ash by water washing to prepare industrial salt; the rest part is treated at high temperature, heavy metal is completely solidified in the crystal lattice of the solid product, dioxin is thoroughly decomposed, and secondary synthesis conditions are not available; high-temperature flue gas is subjected to multi-stage adsorption and dust collection and then reaches the standard and is discharged; the eluent is recycled after being treated, and zero emission is realized. The reduction, the resource utilization and the harmlessness of the waste incineration fly ash disposal are completely realized.
In some embodiments of the present invention, the system for co-processing fly ash by washing and desalting with water and combining with a cement kiln further comprises: the cement kiln waste heat utilization unit comprises a grate cooler and a steam boiler, and the grate cooler is respectively connected with the steam boiler and the water washing fly ash dryer.
In another aspect of the present invention, the present invention provides a method for co-processing of a fly ash washing and desalting combined cement kiln, which is performed by using the system for co-processing of a fly ash washing and desalting combined cement kiln according to an embodiment of the present invention, and according to a specific embodiment of the present invention, the method comprises:
(1) and (3) fly ash elution: desalting the fly ash, preparing fly ash slurry with the mass concentration of 20-30% by mixing the fly ash and the process water, and sequentially feeding the fly ash slurry into the water washing reactor and an elution ash/eluent separation device for carrying out fly ash water washing dechlorination treatment to obtain elution ash and eluent;
(2) purifying the eluent: purifying the eluent, namely adding an alkaline solution, a heavy metal remover and a hardness remover into the eluent in the step (1) for treatment, removing heavy metals in the eluent and reducing the hardness of the eluent, and then sequentially performing sand filtration, pH value adjustment and fine filtration to obtain purified eluent;
(3) evaporation salt preparation: performing multi-stage evaporation on the purified eluent in the step (2) to prepare crystalline salt, and sequentially performing preheating treatment, falling film evaporation treatment, forced circulation evaporation treatment and cooling crystallization treatment on the purified eluent to obtain sodium salt and potassium salt;
(4) and (3) drying: drying the eluted ash in the step (1), and drying the eluted ash by using the waste heat of the flue gas of the cement kiln to obtain dry ash;
(5) calcining in a kiln: and (4) calcining the dried ash obtained in the step (4), solidifying heavy metals, decomposing dioxin, and preparing cement clinker.
Therefore, according to the method for the co-processing of the fly ash by the washing and desalting combined cement kiln, a washing dechlorination technology and a cement kiln high-temperature calcination technology are coupled, and a special multistage countercurrent rinsing technology is adopted, so that the dechlorination effect is good, the water consumption is low, and no dust is raised. The method adopts alkaline elution and secondary heavy metal trapping, so that the transfer of heavy metals and dioxin in the fly ash is low; the MVR evaporation desalination technology is adopted, salt is produced as a byproduct, and condensed water is recycled, so that the energy consumption is low and no pollution is caused; the fly ash is dried by adopting the waste heat of the cement kiln, so that the interference of the fly ash to the cement kiln is reduced, the energy is saved, and the emission is reduced; the fly ash is calcined at high temperature by adopting the cement kiln, so that the heavy metal and dioxin are thoroughly treated, and the method is safe and environment-friendly and has no aftereffect. The technology extracts chloride in fly ash by water washing to prepare industrial salt; the rest part is treated at high temperature, heavy metal is completely solidified in the crystal lattice of the solid product, dioxin is thoroughly decomposed, and secondary synthesis conditions are not available; high-temperature flue gas is subjected to multi-stage adsorption and dust collection and then reaches the standard and is discharged; the eluent is recycled after being treated, and zero emission is realized. The reduction, the resource utilization and the harmlessness of the waste incineration fly ash disposal are completely realized.
In some embodiments of the present invention, the method for co-processing fly ash by washing and desalting with water and combining with a cement kiln further comprises: adding a flocculating agent to the elution ash/eluent in the step (1) in the separation process to improve the separation efficiency. This contributes to obtaining elution ash having a water content of less than 40% and an eluate having a solid content of less than 1%.
In some embodiments of the present invention, the method for co-processing fly ash by washing and desalting with water and combining with a cement kiln further comprises: and (2) performing multi-stage countercurrent elution in the elution processes of the fly ash water washing reaction and the elution ash/eluent separation in the step (1), wherein the preferred number of elution stages is 2-4. Therefore, the removal rate of chloride ions in the fly ash can be obviously improved.
In some embodiments of the present invention, the method for co-processing fly ash by washing and desalting with water and combining with a cement kiln further comprises: and (3) adopting multi-stage removal in the heavy metal removal process in the step (2). Thereby, the removal rate of heavy metals in the eluent can be remarkably reduced.
In some embodiments of the present invention, the method for co-processing fly ash by washing and desalting with water and combining with a cement kiln further comprises: in the step (3), supplementary steam in the falling film evaporation and forced circulation process is introduced from a steam boiler, the temperature rise of the pretreatment is 40-90 ℃, the temperature range of the falling film evaporation process is 60-110 ℃, and the temperature range of the forced circulation evaporation process is 70-130 ℃. Thereby, the energy consumption of the evaporation process can be significantly reduced.
In some embodiments of the present invention, the method for co-processing fly ash by washing and desalting with water and combining with a cement kiln further comprises: and (4) in the step (3), carrying out pretreatment, falling film evaporation and forced circulation evaporation, wherein steam in the mother liquor preheating process comes from a waste heat power generation boiler in a cement plant. Therefore, the waste heat of the cement kiln can be fully utilized.
In some embodiments of the present invention, the method for co-processing fly ash by washing and desalting with water and combining with a cement kiln further comprises: and (4) leading the drying heat source in the step (4) to recover the waste heat of the grate cooler of the cement kiln, wherein the temperature of the flue gas in the drying process is 120-280 ℃. Therefore, the waste heat of the cement kiln can be fully utilized.
In some embodiments of the present invention, the method for co-processing fly ash by washing and desalting with water and combining with a cement kiln further comprises: and (4) feeding the dry fly ash in the step (5) into a fly ash inlet of the rotary kiln through a feeding device, wherein the calcination temperature of the fly ash is above 1400 ℃, and the retention time of the fly ash in the cement kiln is not less than 2 minutes. Therefore, the heavy metals in the fly ash can be solidified in the cement crystal lattice by fully utilizing the high temperature of the cement kiln, and the dioxin is completely decomposed and is thoroughly treated without aftereffects.
Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings.
FIG. 1 is a schematic view of a fly ash elution unit and an eluent purification unit for the cooperative treatment of the fly ash washing desalination combined cement kiln of the present invention.
FIG. 2 is a schematic diagram of an evaporative salt-making unit for the co-treatment of a fly ash washing desalination combined cement kiln.
FIG. 3 is a schematic diagram of a drying unit and a cement kiln calcining unit of the present invention for the co-treatment of a fly ash washing desalination combined cement kiln.
FIG. 4 is a schematic flow chart of the method for co-processing fly ash by washing and desalting with water and combining a cement kiln.
Wherein: a fly ash elution unit 100, a mixer 101, a water washing reactor 102, an elution ash/liquid separator 103, an elution liquid tank 104, an elution liquid purification unit 200, a heavy metal removal tank 201, a hardness removal reactor 202, a precipitate removal device 203, a concentration and precipitation device 204, a multi-stage filtration device 205, a Ph adjusting device 206, an evaporation salt making unit 300, a preheating heat exchanger 301, a vapor compressor 302, a crystallization separator 303, a thickener 304, an enamel kettle 305, a potassium salt centrifuge 306, a potassium mother liquid tank 307, a potassium mother liquid heat exchanger 308, a sodium mother liquid tank 309, a sodium salt centrifuge 310, a forced circulation evaporator 311, a gas-liquid separator 312, a falling film evaporator 313, a distilled water tank 314, a drying unit 400, a water washing fly ash conveyor 401, a water washing fly ash discharger 402, a water washing fly ash dryer 403, a drying fly ash collector 404, a drying elevator 405, a kiln-entering calcination unit 500, a fly ash purification unit 200, a heavy metal removal tank 201, a hardness removal reactor 202, a precipitate removal device 203, a concentration and precipitation device 204, a potassium mother liquid separator 307, a sodium salt making unit 310, a forced circulation evaporator 311, a drying unit, The device comprises a kiln entering fly ash metering device 501, a cement kiln 502, a grate cooler 503 and a steam boiler 504.
Detailed Description
In order that those skilled in the art will better understand the technical solutions of the present invention, the present invention will be further described in detail with reference to specific examples. The following examples are illustrative only and are not to be construed as limiting the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications.
According to the embodiment of the invention, waste incineration fly ash, kiln ash or secondary fly ash generated by high-temperature treatment can be used as raw materials to carry out washing desalination and cement kiln co-treatment.
In one aspect of the invention, the invention provides a system for the co-treatment of fly ash washing and desalting combined with a cement kiln. According to an embodiment of the invention, the system comprises: an eluent outlet of the fly ash eluting unit is connected with an inlet of the eluent purifying unit, an outlet of the eluent purifying unit is connected with an inlet of the evaporation salt-making unit, an eluting ash outlet of the fly ash eluting unit is connected with the drying unit, and an outlet of the drying unit is connected with the kiln-entering calcining unit; the fly ash elution unit comprises a mixer, a water washing reactor and an elution ash/liquid separator, wherein a fly ash inlet of the mixer is respectively connected with an outlet of a fly ash metering device and an outlet of a water distribution metering device, an outlet of the mixer is connected with the water washing reactor, an outlet of the water washing reactor is connected with an inlet of the elution ash/liquid separator, an elution ash outlet of the elution ash/liquid separator is connected with the drying unit, and an eluent outlet of the elution ash/liquid separator is connected with the eluent purification unit; the eluent purification unit comprises a heavy metal removal reactor, a hardness removal reactor, a concentration and precipitation device, a precipitate removal device, a multistage filtering device and a Ph adjusting device, wherein an inlet of the heavy metal removal reactor is connected with an eluent outlet of the elution ash/liquid separator, an outlet of the heavy metal removal reactor is connected with the hardness removal reactor, an outlet of the hardness removal reactor is connected with an inlet of the precipitate removal device, a precipitate outlet of the precipitate removal device is connected with the water washing reactor, an eluent outlet of the precipitate removal device is connected with an inlet of the concentration and precipitation device, an underflow outlet of the concentration and precipitation device is connected with the hardness removal reactor, an overflow outlet of the concentration and precipitation device is connected with an inlet of the multistage filtering device, an outlet of the multistage filtering device is connected with an inlet of the Ph adjusting device, the outlet of the Ph adjusting device is connected with the inlet of the evaporation water supply tank; the evaporation salt-making unit comprises a preheating heat exchanger, a steam compressor, a crystallization separator, a thickener, an enamel kettle, a sylvite centrifuge, a sylvite mother liquor tank, a sylvite mother liquor heat exchanger, a sodium mother liquor tank, a sodium salt centrifuge, a forced circulation evaporator, a gas-liquid separator, a falling-film evaporator and a distilled water tank, wherein the outlet of an evaporation water supply tank is connected with the preheating heat exchanger, the outlet of the preheating heat exchanger is connected with the falling-film evaporator, the outlet of the falling-film evaporator is respectively connected with the gas-liquid separator and the forced circulation evaporator, the outlet of the gas-liquid separator is connected with the steam compressor, the outlet of the steam compressor is respectively connected with the falling-film evaporator and the forced circulation evaporator, the outlet of the forced circulation evaporator is connected with the outlet of the crystallization separator, and the outlet of the crystallization separator is respectively connected with the steam compressor, the potassium salt tank, the evaporator and the evaporator are respectively, The thickener is connected with the sodium salt centrifugal machine and the enamel kettle respectively, the outlet of the sodium salt centrifugal machine is connected with the sodium mother liquor tank, the outlet of the enamel kettle is connected with the potassium salt centrifugal machine, the potassium salt centrifugal machine is connected with the potassium mother liquor tank, the potassium salt mother liquor tank is connected with the potassium mother liquor heat exchanger, and the forced circulation heat exchanger is connected with the sodium mother liquor tank and the potassium mother liquor heat exchanger respectively; the drying unit comprises a washing fly ash conveyor, a washing fly ash feeder, a washing fly ash dryer and a drying fly ash collector, wherein the outlet of the washing fly ash conveyor is connected with the inlet of the washing fly ash feeder, the outlet of the washing fly ash feeder is connected with the inlet of the washing fly ash dryer, the outlet of the washing fly ash dryer is connected with the inlet of the drying fly ash collector, and the outlet of the drying fly ash collector is connected with the calcining unit in the kiln. The kiln entering calcining unit comprises a dry fly ash hoist, a kiln entering fly ash metering device and a cement kiln, wherein the outlet of the dry fly ash hoist is connected with the kiln entering fly ash metering device, and the outlet of the kiln entering fly ash metering device is connected with the cement kiln. The inventor finds that the dechlorination effect is good, the water consumption is low and no dust is raised by coupling the water washing dechlorination technology with the high-temperature calcination technology of the cement kiln and adopting the special multi-stage countercurrent rinsing technology. (ii) a The method adopts alkaline elution and secondary heavy metal trapping, so that the transfer of heavy metals and dioxin in the fly ash is low; the MVR evaporation desalination technology is adopted, salt is produced as a byproduct, and condensed water is recycled, so that the energy consumption is low and no pollution is caused; the fly ash is dried by adopting the waste heat of the cement kiln, so that the interference of the fly ash to the cement kiln is reduced, the energy is saved, and the emission is reduced; the fly ash is calcined at high temperature by adopting the cement kiln, so that the heavy metal and dioxin are thoroughly treated, and the method is safe and environment-friendly and has no aftereffect. The technology extracts chloride in fly ash by water washing to prepare industrial salt; the rest part is treated at high temperature, heavy metal is completely solidified in the crystal lattice of the solid product, dioxin is thoroughly decomposed, and secondary synthesis conditions are not available; high-temperature flue gas is subjected to multi-stage adsorption and dust collection and then reaches the standard and is discharged; the eluent is recycled after being treated, and zero emission is realized. The reduction, the resource utilization and the harmlessness of the waste incineration fly ash disposal are completely realized.
The system and reverse detailed description of the fly ash water-washing desalination combined cement kiln co-treatment of the present invention are described in detail below with reference to fig. 1-3. According to an embodiment of the invention the system comprises: a fly ash elution unit 100, an eluent purification unit 200, an evaporation salt making unit 300, a drying unit 400 and a kiln-entering calcination unit 500.
According to the embodiment of the invention, the fly ash elution unit 100 comprises a mixer 101, a water washing reactor 102, an elution ash/liquid separator 103 and an elution liquid tank 104, wherein a fly ash inlet of the mixer 101 is respectively connected with a fly ash metering device outlet and a water distribution metering device outlet, an outlet of the mixer 101 is connected with the water washing reactor 102, an outlet of the water washing reactor 102 is connected with an inlet of the elution ash/liquid separator 103, an elution ash outlet of the elution ash/liquid separator 103 is connected with a drying unit 400, and an elution outlet of the elution ash/liquid separator 103 is connected with the elution liquid tank 104.
According to the embodiment of the invention, the elution process adopts first-stage to N-stage water washing according to the chlorine content requirements of the raw material and the water-washed fly ash, each stage of water washing process is not limited to only adopting one elution ash/liquid separator, and 1 to N separation devices can be adopted according to the chlorine content requirements of the raw material and the water-washed fly ash. Another advantage of the present invention is that the fly ash elution process employs multi-stage counter-current rinsing, which significantly reduces water consumption in the fly ash elution process. The countercurrent rinsing in the invention means that when the first-stage, second-stage and … … N-stage are adopted for elution, the water washing liquid of the second stage is used as water for the first-stage water-washing fly ash pulping and distributing, the water washing liquid of the third stage is used as water for the second-stage water-washing fly ash pulping and distributing, … …, and the water washing liquid of the Nth stage is used as water for the Nth-1-stage water-washing fly ash pulping and distributing. It is noted that the skilled person can select the multi-stage rinsing and/or the multiple separation devices to be used according to the actual needs.
According to the embodiment of the invention, the fly ash elution process adopts multi-stage countercurrent rinsing, so that the water consumption in the elution process is greatly reduced, the dechlorination effect reaches more than 90 percent, and the problems of high water consumption and high content of chloride ions in the water-washed fly ash in the fly ash elution process are solved. The inventor finds that the water washing reactor and the elution ash/liquid separator in the fly ash elution process have no special requirements, and only the water washing fly ash with the water content of less than 40 percent and the water washing liquid with the solid content of less than 1 percent are obtained after the fly ash is eluted. In accordance with embodiments of the present invention, the inventors have discovered that plate and frame filter presses and centrifuges are presently preferred for the elution ash/liquid separator.
According to the embodiment of the present invention, the eluent purification unit 200 comprises a heavy metal removal tank 201, a hardness removal reactor 202, a precipitate removal device 203, a concentration and precipitation device 204, a multi-stage filtration device 205, and a Ph adjustment device 206, wherein an inlet of the heavy metal removal reactor 201 is connected with an eluent outlet of the elution ash/liquid separator 103, an outlet of the heavy metal removal reactor 201 is connected with the hardness removal reactor 202, an outlet of the hardness removal reactor 202 is connected with an inlet of the precipitate removal device 203, a precipitate outlet of the precipitate removal device 203 is connected with the water washing reactor 102, an eluent outlet of the precipitate removal device 203 is connected with an inlet of the concentration and precipitation device 204, a bottom flow outlet of the concentration and precipitation device 204 is connected with the hardness removal reactor 202, an overflow outlet of the concentration and precipitation device 204 is connected with an inlet of the multi-stage filtration device 205, an outlet of the multi-stage filtration device 205 is connected with an inlet of the Ph adjustment device 206, the outlet of the Ph adjusting device 206 is connected with the inlet of the evaporation water supply tank;
according to the embodiment of the invention, according to the characteristics of the eluent and the requirement of the purified water quality, the heavy metal in the eluent is removed in multiple stages, so that the heavy metal in the eluent can be effectively removed; the filtration process of the eluent adopts multi-stage filtration, which is beneficial to effectively removing solid suspended matters in the eluent. According to the embodiment of the invention, through adopting multi-stage heavy metal removal, hardness removal and solid suspension filtration, impurities such as suspended matters, calcium and magnesium ions, heavy metals and the like in the washing liquid are removed after the washing liquid is subjected to physical and chemical purification treatment, so that the requirements of an evaporation salt-making process and the quality of crystallized salt are met.
According to the embodiment of the invention, the evaporation salt-making unit 300 comprises a preheating heat exchanger 301, a vapor compressor 302, a crystallization separator 303, a thickener 304, an enamel kettle 305, a potassium salt centrifuge 306, a potassium mother liquor tank 307, a potassium mother liquor heat exchanger 308, a sodium mother liquor tank 309, a sodium salt centrifuge 310, a forced circulation evaporator 311, a vapor-liquid separator 312, a falling-film evaporator 313 and a distilled water tank 314, wherein an outlet of the evaporation water supply tank is connected with the preheating heat exchanger 301, an outlet of the preheating heat exchanger 301 is connected with the falling-film evaporator 313, outlets of the falling-film evaporator 313 are respectively connected with the vapor-liquid separator 312 and the forced circulation evaporator 311, an outlet of the vapor-liquid separator 312 is connected with the vapor compressor 302, outlets of the vapor compressor 302 and the forced circulation evaporator 311 are respectively connected with the falling-film evaporator 312 and the forced circulation evaporator 311, an outlet of the forced circulation evaporator 311 is connected with an outlet of the crystallization separator 303, an outlet of the crystallization separator 303 is respectively connected with the vapor compressor 302, the thickener 304 and the evaporator 302, The thickener 304 is connected, the thickener 304 is respectively connected with a sodium salt centrifuge 310 and an enamel kettle 305, the outlet of the sodium salt centrifuge 310 is connected with a sodium mother liquor tank 309, the outlet of the enamel kettle 305 is connected with a potassium salt centrifuge 306, the potassium salt centrifuge 306 is connected with a potassium mother liquor tank 307, the potassium salt mother liquor tank 307 is connected with a potassium mother liquor heat exchanger 308, and the forced circulation heat exchanger 311 is respectively connected with the sodium mother liquor tank 309 and the potassium mother liquor heat exchanger 308.
According to the embodiment of the invention, whether the salt is separated or not can be set according to the characteristics of the purified eluent and the requirements of the quality of the crystallized salt, and if the salt is not separated, the enamel kettle 305, the potassium salt centrifuge 306, the potassium mother liquor tank 307, the potassium mother liquor heat exchanger 308 and the sodium mother liquor tank 309 can be not set. In order to reduce energy consumption, evaporation condensate water heat exchange, non-condensation heat exchange and the like are generally adopted in the preheating heat exchange process, and heat energy in the evaporation process is fully utilized. And separating soluble salt and water in the water washing liquid by evaporation to obtain crystalline salt with the total amount of sodium chloride and potassium chloride not less than 90%, and recycling the evaporated condensate water.
According to the embodiment of the present invention, the drying unit 400 includes a washing fly ash conveyor 401, a washing fly ash discharger 402, a washing fly ash dryer 403, a drying fly ash collector 404 and a drying fly ash hoist 405, an outlet of the washing fly ash conveyor 401 is connected to an inlet of the washing fly ash discharger 402, an outlet of the washing fly ash discharger 402 is connected to an inlet of the washing fly ash dryer 403, an outlet of the washing fly ash dryer 403 is connected to an inlet of the drying fly ash collector 404, and an outlet of the drying fly ash collector 404 is connected to the drying fly ash hoist 405.
According to the embodiment of the invention, the fly ash drying process has no special requirements on drying equipment and dust collecting equipment, and only the moisture content of the washed fly ash is reduced through drying, so that the dried fly ash with the chloride ion content of less than 1% and the moisture content of less than 5% is obtained. The inventor finds that in order to meet the requirement of environmental protection, the inlet temperature of the hot drying air is required to be 300 ℃ in the drying process, preferably 180 ℃ in the drying process, pulse blowing is adopted in the ash removal mode of the dust collector, and the dust collector is required to meet the requirement that the concentration of the dust outlet is not higher than 10mg/m for carrying out the cultivation. In addition, the inventor also finds that a mixed drying measure is needed to avoid fly ash blockage, agglomeration and wall hanging in the drying and conveying processes, and fly ash special conveying equipment with functions of scattering, mixing and the like is adopted, so that the fly ash conveying effect is guaranteed, and the equipment and pipeline blockage is reduced.
According to the embodiment of the invention, the kiln entering calcination unit 500 comprises a kiln entering fly ash metering device 501, a cement kiln 502, a grate cooler 503 and a steam boiler 504, wherein the kiln entering fly ash metering device 501 is connected with an outlet of the dry fly ash hoist 405, an outlet of the kiln entering fly ash metering device 501 is connected with the cement kiln 502, a clinker outlet of the cement kiln 502 is connected with the grate cooler 503, and a smoke outlet of the grate cooler 503 is connected with the steam boiler 504. The inventor finds that the cement kiln has no special requirement on the moisture of fly ash entering the kiln, if the fly ash is not dried, the fly ash is sprayed into the kiln to meet the process requirement, only the high moisture content of the fly ash can increase the energy consumption of the cement kiln, and the energy consumption and carbon emission of per ton of clinker in the cement kiln system are reduced by drying the fly ash before entering the kiln.
The specific process is that the material calcining temperature in the calcining area of the cement kiln and the highest temperature of gas in the kiln respectively reach 1400 ℃ and 2000 ℃, which are far higher than 1100 ℃ required by a hazardous waste incinerator, the dioxin can be thoroughly decomposed at the stage, the flue gas in the cement kiln is cooled quickly in an area of 200-450 ℃, and the re-synthesis of substances such as dioxin, bark and the like is reduced; the retention time of the materials in the cement kiln is longer, the retention time of gas in an area with the temperature of over 1100 ℃ is as long as 8s, and the burning rate of harmful components can reach over 99.99 percent; the alkaline atmosphere in the cement kiln is favorable for adsorbing acid gas and SO2HC1 and HF have strong neutralizing effect(ii) a The final product of the cement kiln treatment is cement, no waste residue is generated, and heavy metals are solidified in clinker in the clinker calcination process, so that the heavy metals in fly ash can be effectively prevented from being dissolved out, and the secondary pollution to the environment is avoided.
In another aspect of the invention, the invention provides a method for the water washing desalination of fly ash and the cooperative treatment of a cement kiln. According to an embodiment of the invention, the method is carried out by adopting the system for the co-treatment of the water washing desalination and cement kiln of the fly ash. According to an embodiment of the invention, (1) fly ash elution: desalting the fly ash, preparing fly ash slurry with the mass concentration of 20-30% by mixing the fly ash and the process water, and sequentially feeding the fly ash slurry into the water washing reactor and an elution ash/eluent separation device for carrying out fly ash water washing dechlorination treatment to obtain elution ash and eluent; (2) purifying the eluent: purifying the eluent, namely adding an alkaline solution, a heavy metal remover and a hardness remover into the eluent in the step (1) for treatment, removing heavy metals in the eluent and reducing the hardness of the eluent, and then sequentially performing sand filtration, pH value adjustment and fine filtration to obtain purified eluent; (3) evaporation salt preparation: performing multi-stage evaporation on the purified eluent in the step (2) to prepare crystalline salt, and sequentially performing preheating treatment, falling film evaporation treatment, forced circulation evaporation treatment and cooling crystallization treatment on the purified eluent to obtain sodium salt and potassium salt; (4) and (3) drying: drying the eluted ash in the step (1), and drying the eluted ash by using the waste heat of the flue gas of the cement kiln to obtain dry ash; (5) calcining in a kiln: and (4) calcining the dried ash obtained in the step (4), solidifying heavy metals, decomposing dioxin, and preparing cement clinker. The inventor finds that the dechlorination effect is good, the water consumption is low and no dust is raised by coupling the water washing dechlorination technology with the high-temperature calcination technology of the cement kiln and adopting the special multi-stage countercurrent rinsing technology. (ii) a The method adopts alkaline elution and secondary heavy metal trapping, so that the transfer of heavy metals and dioxin in the fly ash is low; the MVR evaporation desalination technology is adopted, salt is produced as a byproduct, and condensed water is recycled, so that the energy consumption is low and no pollution is caused; the fly ash is dried by adopting the waste heat of the cement kiln, so that the interference of the fly ash to the cement kiln is reduced, the energy is saved, and the emission is reduced; the fly ash is calcined at high temperature by adopting the cement kiln, so that the heavy metal and dioxin are thoroughly treated, and the method is safe and environment-friendly and has no aftereffect. The technology extracts chloride in fly ash by water washing to prepare industrial salt; the rest part is treated at high temperature, heavy metal is completely solidified in the crystal lattice of the solid product, dioxin is thoroughly decomposed, and secondary synthesis conditions are not available; high-temperature flue gas is subjected to multi-stage adsorption and dust collection and then reaches the standard and is discharged; the eluent is recycled after being treated, and zero emission is realized. The reduction, the resource utilization and the harmlessness of the waste incineration fly ash disposal are completely realized. It should be noted that the features and advantages described above for the system for co-disposal of fly ash washing and desalting combined cement kiln are also applicable to the method for co-disposal of fly ash washing and desalting combined cement kiln, and are not described herein again.
The method of the present invention for the co-treatment of fly ash with water washing desalination combined with cement kiln is described in detail below with reference to fig. 4, and according to an embodiment of the present invention, the method comprises:
fly ash elution S100: washing fly ash with water, eluting ash/separating eluent
According to the embodiment of the invention, the fly ash and the process water are firstly prepared into fly ash slurry with the mass concentration of 20-30%, and the fly ash slurry is sequentially sent into the water washing reactor and the elution ash/eluent separation device for carrying out the water washing dechlorination treatment of the fly ash, so as to obtain elution ash and eluent. Thereby, the soluble chloride salt in the fly ash can be removed significantly.
The concentration of the fly ash slurry into which the fly ash and the process water are formulated is not particularly limited and can be selected as desired by those skilled in the art according to one embodiment of the present invention. According to the specific embodiment of the present invention, the number of rinsing times of the fly ash is not particularly limited, and those skilled in the art can determine according to actual conditions that the number of washing times varies according to the chloride ion content in the fly ash, and the higher the chloride ion content in the fly ash is, the more washing times are required. According to the embodiment of the invention, the characteristics of the countercurrent rinsing are not limited to the water washing liquid of the N grade as the pulp preparation water of the N-1 grade, and can be selected according to actual needs. According to the specific embodiment of the present invention, the elution times of the eluents in each stage of rinsing are not particularly limited, and may be selected from 1 to n times according to actual needs, and the times of different stages are not required to be consistent. According to the embodiment of the invention, the elution of fly ash after elution and the elution are not strictly limited, and in order to better meet the requirements of downstream units, a person skilled in the art usually requires that fly ash is washed and separated by counter current to remove soluble salts in fly ash, so as to obtain water-washed fly ash with the water content of less than 40% and water-washed liquid with the solid content of less than 1%.
Eluent purification S200: purifying the eluent
According to the embodiment of the invention, the eluent is firstly added with alkaline solution, heavy metal remover and hardness remover for treatment, heavy metal in the eluent is removed and the hardness of the eluent is reduced, and then sand filtration, pH value adjustment and fine filtration are sequentially carried out to obtain purified eluent. Therefore, the content of solid suspended matters, heavy metal ions and calcium and magnesium ions in the eluent is reduced, and the purification index of the eluent is improved.
According to an embodiment of the present invention, the inventors found that the order, kind and amount of the alkaline solution, the heavy metal removal agent and the hardness removal agent added to the eluent are not specifically limited, and can be determined by those skilled in the art according to actual conditions. The precipitate removing device according to the embodiment of the present invention is not particularly limited, and a centrifugal separation apparatus or a plate and frame separation apparatus is generally selected by those skilled in the art in consideration of technical maturity and use effect. According to the embodiment of the present invention, the inventors found that the number of times of filtration of the eluent is not significantly limited, and the order of the addition position of the Ph adjusting agent and the filtration equipment is not significantly limited, but the addition position of the Ph adjusting agent needs to be after the precipitate removing device. According to the embodiment of the invention, the purification index of the eluent is not strictly limited, and the eluent is generally required to be subjected to physicochemical purification treatment by a person skilled in the art so as to meet the requirements of evaporation salt-making process and quality of crystallized salt
Evaporation salt making S300: subjecting the purified eluate to evaporative desalination
According to the embodiment of the invention, purified eluent is subjected to multi-stage evaporation to prepare crystalline salt, evaporated condensate water is used as process water or flushing water in a flying elution process and an eluent purification process, and the purified eluent is sequentially subjected to preheating treatment, falling film evaporation treatment, forced circulation evaporation treatment and cooling crystallization treatment to obtain sodium salt and potassium salt. Therefore, the energy consumption in the evaporation process is reduced by adopting a steam mechanical recompression evaporation process.
According to an embodiment of the present invention, the inventors have found that the waste heat such as sensible heat, sensible heat of non-condensed steam, latent heat of non-condensed steam, etc. generated in the evaporation process can be fully utilized to preheat the evaporation raw material, and the steam or flue gas of the cement kiln can be utilized as the heat source in the preheating process. According to the embodiment of the invention, whether the salt separation is adopted in the evaporation salt making process is mainly determined by the requirements of the owner, and no clear limitation is made on whether the salt separation is adopted.
And (5) drying S400: drying the elution ash
According to the embodiment of the invention, the eluted ash is dried, and the mixed ash is dried by using the residual heat of the flue gas of the cement kiln to obtain the dried ash. Therefore, the problems of wall hanging, blockage and hardening in the process of conveying the eluted ash into the kiln are obviously reduced, the energy consumption of water evaporation in the process of calcining the fly ash in the cement kiln is reduced, and the carbon emission is reduced.
According to one embodiment of the present invention, the inventor finds that the heat source medium in the drying process has no obvious requirement, flue gas and steam can be selected, an indirect drying mode can be selected, the temperature of the heat source medium is not limited obviously, and in order to avoid the generation of toxic and harmful gas in the fly ash in the drying process, the temperature of the heat source is generally required to be below 300 ℃ by those skilled in the art.
Calcining in a cement kiln S500: calcining the dry fly ash/elution ash
According to the embodiment of the invention, the dry ash/elution ash is calcined, organic pollutants such as dioxin in the fly ash can be thoroughly decomposed in the high-temperature environment of the cement kiln, the flue gas in the cement kiln is cooled quickly in the region of 200-450 ℃, the resynthesis of substances such as dioxin, bark and the like is reduced, the retention time of the fly ash in the cement kiln is longer, and the incineration rate of harmful components can reach more than 99.99%. Thus, heavy metals can be solidified and dioxin can be decomposed by calcination in a cement kiln.
According to the embodiment of the invention, chlorine salt in the fly ash is extracted by water washing to prepare industrial salt, heavy metal is completely solidified in crystal lattices of a solid product by high-temperature treatment of the water-washed fly ash, dioxin is thoroughly decomposed and secondary synthesis conditions are not available; high-temperature flue gas is subjected to multi-stage adsorption and dust collection and then reaches the standard and is discharged; the eluent is recycled after being treated, and zero emission is realized. Completely realizes the harmlessness, reduction and reclamation of the fly ash treatment.
According to the scheme, the system and the method for the cooperative treatment of the fly ash by the washing and desalting combined cement kiln completely realize reduction, reclamation and harmlessness of fly ash treatment.
In the present invention, unless otherwise expressly stated or limited, the terms "connected" and "connected" are to be construed broadly, e.g., as meaning either a fixed connection or a removable connection, or an integral part; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the description of the present invention, it is to be understood that the terms "upper", "lower", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described, it is understood that the embodiments are illustrative and not restrictive, that various changes, modifications, substitutions and alterations may be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A system for cooperative treatment of fly ash washing and desalting combined cement kiln is characterized in that an eluent outlet of a fly ash eluting unit is connected with an inlet of an eluent purifying unit, an outlet of the eluent purifying unit is connected with an inlet of an evaporation salt making unit, an eluting ash outlet of the fly ash eluting unit is connected with a drying unit, and an outlet of the drying unit is connected with a kiln entering calcining unit;
the fly ash elution unit comprises a mixer, a water washing reactor and an elution ash/liquid separator, wherein a fly ash inlet of the mixer is respectively connected with an outlet of a fly ash metering device and an outlet of a water distribution metering device, an outlet of the mixer is connected with the water washing reactor, an outlet of the water washing reactor is connected with an inlet of the elution ash/liquid separator, an elution ash outlet of the elution ash/liquid separator is connected with the drying unit, and an eluent outlet of the elution ash/liquid separator is connected with the eluent purification unit;
the eluent purification unit comprises a heavy metal removal reactor, a hardness removal reactor, a concentration and precipitation device, a precipitate removal device, a multistage filtering device and a Ph adjusting device, wherein an inlet of the heavy metal removal reactor is connected with an eluent outlet of the elution ash/liquid separator, an outlet of the heavy metal removal reactor is connected with the hardness removal reactor, an outlet of the hardness removal reactor is connected with an inlet of the precipitate removal device, a precipitate outlet of the precipitate removal device is connected with the water washing reactor, an eluent outlet of the precipitate removal device is connected with an inlet of the concentration and precipitation device, an underflow outlet of the concentration and precipitation device is connected with the hardness removal reactor, an overflow outlet of the concentration and precipitation device is connected with an inlet of the multistage filtering device, an outlet of the multistage filtering device is connected with an inlet of the Ph adjusting device, the outlet of the Ph adjusting device is connected with the inlet of the evaporation water supply tank;
the evaporation salt-making unit comprises a preheating heat exchanger, a steam compressor, a crystallization separator, a thickener, an enamel kettle, a sylvite centrifuge, a sylvite mother liquor tank, a sylvite mother liquor heat exchanger, a sodium mother liquor tank, a sodium salt centrifuge, a forced circulation evaporator, a gas-liquid separator, a falling-film evaporator and a distilled water tank, wherein the outlet of an evaporation water supply tank is connected with the preheating heat exchanger, the outlet of the preheating heat exchanger is connected with the falling-film evaporator, the outlet of the falling-film evaporator is respectively connected with the gas-liquid separator and the forced circulation evaporator, the outlet of the gas-liquid separator is connected with the steam compressor, the outlet of the steam compressor is respectively connected with the falling-film evaporator and the forced circulation evaporator, the outlet of the forced circulation evaporator is connected with the outlet of the crystallization separator, and the outlet of the crystallization separator is respectively connected with the steam compressor, the potassium salt tank, the evaporator and the evaporator are respectively, The thickener is connected with the sodium salt centrifugal machine and the enamel kettle respectively, the outlet of the sodium salt centrifugal machine is connected with the sodium mother liquor tank, the outlet of the enamel kettle is connected with the potassium salt centrifugal machine, the potassium salt centrifugal machine is connected with the potassium mother liquor tank, the potassium salt mother liquor tank is connected with the potassium mother liquor heat exchanger, and the forced circulation heat exchanger is connected with the sodium mother liquor tank and the potassium mother liquor heat exchanger respectively;
the drying unit comprises a washing fly ash conveyor, a washing fly ash feeder, a washing fly ash dryer and a drying fly ash collector, wherein the outlet of the washing fly ash conveyor is connected with the inlet of the washing fly ash feeder, the outlet of the washing fly ash feeder is connected with the inlet of the washing fly ash dryer, the outlet of the washing fly ash dryer is connected with the inlet of the drying fly ash collector, and the outlet of the drying fly ash collector is connected with the calcining unit in the kiln;
the kiln entering calcining unit comprises a dry fly ash hoist, a kiln entering fly ash metering device and a cement kiln, wherein the outlet of the dry fly ash hoist is connected with the kiln entering fly ash metering device, and the outlet of the kiln entering fly ash metering device is connected with the cement kiln.
2. The system of claim 1, further comprising:
the cement kiln waste heat utilization unit comprises a grate cooler and a steam boiler, and the grate cooler is respectively connected with the steam boiler and the water washing fly ash dryer.
3. The system for the co-disposal of the fly ash washing desalination combined cement kiln of any one of claims 1-2 comprises a method for the co-disposal of the fly ash washing desalination combined cement kiln, which is characterized by comprising the following steps:
(1) and (3) fly ash elution: desalting the fly ash, preparing fly ash slurry with the mass concentration of 20-30% by mixing the fly ash and the process water, and sequentially feeding the fly ash slurry into the water washing reactor and an elution ash/eluent separation device for carrying out fly ash water washing dechlorination treatment to obtain elution ash and eluent;
(2) purifying the eluent: purifying the eluent, namely adding an alkaline solution, a heavy metal remover and a hardness remover into the eluent in the step (1) for treatment, removing heavy metals in the eluent and reducing the hardness of the eluent, and then sequentially performing sand filtration, pH value adjustment and fine filtration to obtain purified eluent;
(3) evaporation salt preparation: performing multi-stage evaporation on the purified eluent in the step (2) to prepare crystalline salt, and sequentially performing preheating treatment, falling film evaporation treatment, forced circulation evaporation treatment and cooling crystallization treatment on the purified eluent to obtain sodium salt and potassium salt;
(4) and (3) drying: drying the eluted ash in the step (1), and drying the eluted ash by using the waste heat of the flue gas of the cement kiln to obtain dry ash;
(5) calcining in a kiln: and (4) calcining the dried ash obtained in the step (4), solidifying heavy metals, decomposing dioxin, and preparing cement clinker.
4. The method for co-disposal of fly ash in water washing desalination combined with cement kiln as claimed in claim 3, characterized in that the elution ash/eluent in step (1) is added with flocculant in the separation process to improve the separation efficiency.
5. The method for co-disposal of fly ash in water washing desalination combined with cement kiln as claimed in claim 3, wherein the elution process of the fly ash water washing reaction and elution ash/eluent separation in step (1) adopts multi-stage counter-current elution, and the number of elution stages is preferably 2-4.
6. The method for co-disposal of fly ash through washing and desalting with a cement kiln as claimed in claim 3, wherein the heavy metal removal process in step (2) adopts multi-stage removal.
7. The method for co-processing fly ash by washing and desalting with water and combining a cement kiln as claimed in claim 3, wherein the supplementary steam for the falling film evaporation and forced circulation process in step (3) is introduced from a steam boiler, the temperature rise of the pretreatment is 40-90 ℃, the temperature range of the falling film evaporation process is 60-110 ℃ and the temperature range of the forced circulation evaporation process is 70-130 ℃.
8. The method for co-processing fly ash by washing and desalting with water and combining a cement kiln as claimed in claim 3, wherein the pretreatment, falling film evaporation and forced circulation evaporation are carried out in step (3), and the steam in the mother liquor preheating process is from a cogeneration boiler in a cement plant.
9. The method for co-disposal of fly ash through washing and desalting combined cement kiln as claimed in claim 3, wherein the drying heat source in step (4) is introduced from the waste heat recovery of the grate cooler of the cement kiln, and the flue gas temperature in the drying process is 120-280 ℃.
10. The method for co-disposing fly ash in a washing and desalting combined cement kiln as claimed in claim 3, wherein the dry ash in step (5) is fed into the fly ash inlet at the tail of the rotary kiln by a feeding device, the calcination temperature of the fly ash is above 1400 ℃, and the residence time of the fly ash in the cement kiln is not less than 2 minutes.
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